Seth Patterson
Registered
While manning the front desk at Sabal Palm Sanctuary (where I work) this past November, I met a friendly gentleman who was visiting the Lower Rio Grande Valley of Texas for our annual Birding Festival. After chatting about birds and other such topics, we somehow stumbled onto the conversation of scuba diving, which, not surprisingly, is a bit of an obsession of mine.
My new friend, Richard, asked if I had ever been to, or heard of, La Media Luna in San Luis Potosi, Mexico. After admitting Id heard of it only in passing but knew absolutely nothing otherwise, Richard threw out some descriptive phrases like deep, crystal clear, thermal springs, endemic species and I was absolutely enthralled. Richard mentioned that he drove down there a few times a year to scuba dive and was curious if I would be interested in making the trip some time. Of course, my pragmatic and (justifiably) cautious mind immediately asked if hed feel safe driving from South Texas and into Mexico while transporting tens of thousands of dollars in underwater equipment. His hesitation spoke measures and I swept the idea aside, mentally filing it away under someday, when Mexico is safe again...
Yet, as the days rolled on, the thought of such an incredible place so close to where I live nagged at me insistently. I found myself googling Media Luna, the Rioverde Valley of San Luis Potosi, cost of airfare, hotels, rental cars, dive shops, etc... and before I knew it, I had planned out an entire trip!
With Gwyn out of work for the holidays, we decided to spend the week of Christmas in the small town of Rioverde; scuba diving in the crystal clear, 118 feet deep, thermal-spring fed lake, La Media Luna. Richard was kind enough to join us (though immensely more brave as he drove while we flew).
Hauling our (overly) packed bags, our flight from McAllen, Texas to San Luis Potosi (city), San Luis Potosi (state) was short and uneventful. As it was close to nightfall when we arrived, and we were advised it was best not to travel at night, we picked up our rental car and checked into a nearby hotel where we met one of our Facebook friends, Luis, and his lovely family for dinner. After sharing stories of many fun travels, Luis gave us some great insights to the region and the next morning we set off on the three hour drive from San Luis Potosi to Rioverde. The drive flew by and before long we found ourselves parked in front of Hotel Media Luna where we promptly checked in, transported our luggage to our room, and prepared our gear for diving.
Shortly thereafter, Richard drove into town and introduced us to the owner of one of the local dive shops, Ossiel Martinez. An accomplished technical diver and instructor, Ossiel was an absolute wealth of knowledge and his dive operation, Buceo Media Luna, provided all our rental gear and tanks during our stay. I cannot recommend their services enough, great people who welcomed us as family. Of course, by this point, we were itching to get in the water so Richard led us down the dusty, 9 km road to Media Luna.
Upon arriving, we were rushed by young boys toting wheelbarrows and dollies, all vying for our patronage. After selecting Ossiels regular kid, we quickly found out the reason for this seemingly booming wheelbarrow business as the walk from the parking area to the lake-front was a significant one and hauling multiple tanks by hand an exhausting prospect. After paying our entrance fee to the park, we made our way down to the lake, passing a multitude of small shops, restaurants, and camp sites.
At the lakeside there was a platform dedicated to divers with two ladders for crawling back out of the water. Without hesitation, we donned our gear and dropped straight into the awaiting waters. What a wonderful feeling 82 degree water is! So warm and inviting, especially with the cool breeze blowing down from the mountains. Once situated, Richard led us around the lake, showing us the various landmarks (watermarks?) and teaching us how to navigate.
He took us around the big spring head, which drops conically to 118 feet and down into some of the smaller ones, ranging from 30-60ft in depth. Being engulfed in warm, 84-86 degree water, while hovering over the spring vent was a neat sensation! There were few divers this day so visibility was good, ranging from 50-80+ feet on average. Over the years, great mounds of fine silt have accumulated along the bottom of the lake and a careless diver can easily cause a complete blackout with the kick of his fin. So, the fewer divers around, the clearer things stay, and, luckily, we had few divers during the majority of our stay.
After exploring the spring heads, Richard took us to the petrified forest, where ancient and massive cypress trees collapsed from the bank and plunged into the depths of Media Luna. The mineral-rich waters have encrusted these giant trees, giving them a petrified look. From there, he led us to one of the swim-through caves, which I found absolutely fascinating. I had erroneously assumed these were limestone or some similar karst formed caves, when in fact they are entirely organic. I quickly realized that the walls of the cave were actually root masses from the vegetation above and that the majority of the shoreline was quite literally dense mats of floating vegetation. Poking ones head out of the various skylights throughout the cave found the diver staring out of a small clearing into a dense tangle of grasses and ferns. Swimming to the end of the cave revealed its formation. At 30 feet below, another thermal spring bubbled up, the flow cutting a cave-like path through the islands of vegetation.
Once accustomed to the layout of the lake, Gwyn and I set about taking pictures, trying to document as many species as we could find. Currently there are (at least) 6 species of fish endemic to Media Luna and the surrounding springs as well as several invertebrates, including a species of shrimp and crayfish. We spent six days exploring and taking pictures. Unfortunately, I was only able to squeeze in 12 dives over 5 days but all our dives were quite long (2+ hours on average) and all absolutely lovely. The weather started out acceptably warm but quickly turned cold and, let me tell you, going from 42 degree air into 82 degree water was such a wonderful sensation! It was like dropping into a hot tub. Of course, getting back out wasnt nearly as much fun
We ended up having really fun and successful trip and are so thankful to Richard and Ossiel for all their help. Rioverde was a quiet little town where we enjoyed many of meal at the local restaurants and our hotel was clean and comfortable. What more can one ask for?
If you havent been, I would highly recommend visiting La Media Luna! Its a remarkable lush, aquatic ecosystem raising up from an otherwise arid landscape.
The canal running in front of our hotel transfers water from Media Luna to Rioverde municipal and agricultural uses.
The entrance into Media Luna park.
It's an extremely popular picnic and camping destination for local outdoor enthusiasts.
The canal, running through the park.
The canal where it flows from the lake, depth here is about 6 feet.
Families enjoying the warm waters of Media Luna.
Fall-off the dock diving is always fun...
Looking up...
Gwyn following me into the depths.
Probably my favorite species of the trip, the endemic Curve-bar Cichlids (Cichlasoma labridens).
Papa Curve-bar hurrying his fry along.
A moment of tension between the parents..
Gwyn off exploring the lake.
Another neat little endemic species, the Checkered Pupfish (Cualac tessellatus).
Male checkered Pupfish showing off his lovely markings.
An ancient submerged cypress tree raising up from the depths.
For scale, you can see Gwyn diving amongst the "petrified forest."
Gwyn investigating a spring head at approximately 30 feet below.
Millions of tiny gastropod shells were being exhaled from the thermal vent. It doesn't seem like anyone really understands where they are coming from or even what species they are...
A larger snail peeking out from his shell.
A nocturnal species, the endemic Rioverde Catfish (Ictalurus mexicanus) was often found lingering around the thermal vents during the day.
